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Old March 28th, 2008, 09:09 AM   #9 (permalink)
Billm
Tele-Meister
 
Join Date: Mar 2008
Location: New Jersey
Age: 61
Posts: 224
A 5751 or 12AY7 is almost always a better choice than a 12AT7/ECC81. The 12AT7 is a driver tube, not a preamp. It has lower internal impedance, which is good for high-current applications like driving a reverb tank. But the lower impedance also tends to kill of high frequencies.

You may like the mellower sound, but I'd rather shape the highs with my tone controls rather than letting the tubes eat up tone that I'll never get back.

The 12AU7 is also a driver tube, with even lower impedance and lower gain than the 12AT7.

If you want lower gain, look at Leo's old schematics. You'll never see a 12AT7 in the preamp; it was always a 12AY7 for lower gain or a 12AX7 for higher. He knew what he was doing.
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